Organic semiconductor material and organic electronic device

ABSTRACT

An organic semiconductor material comprising a compound which has a generalized porphyrin skeleton and which has a molecular structure such that the distance from the generalized porphyrin ring plane to the center of each atom forming the generalized porphyrin skeleton, is not more than 1 Å

[0001] The entire disclosures of Japanese Patent Application No.2002-089425 filed on Mar. 27, 2002, Japanese Patent Application No.2002-104639 filed on Apr. 8, 2002 and Japanese Patent Application No.2003-049561 filed on Feb. 26, 2003 including specifications, claims,drawings and summaries are incorporated herein by reference in theirentireties.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to an organic semiconductormaterial and an organic electronic device such as a field effecttransistor. Particularly, it relates to an organic semiconductormaterial comprising a generalized porphyrin compound having a specificstructure, and an organic electronic device employing such a material.

[0004] 2. Discussion of the Background

[0005] Heretofore, as a field effect transistor (hereinafter sometimesreferred to as FET) device, one employing, as a semiconductor layer, aninorganic semiconductor material such as a silicon (Si) or galliumarsenide single crystal, has been widely used. However, in the case ofan inorganic material, it will be treated at a high temperature of atleast 300° C. at the time of its production, whereby it is difficult toemploy a plastic (or resin) for the substrate, and a large energy isrequired for its production. It requires a production process undervacuum, such as vapor deposition, sputtering or CVD, whereby it isdifficult to produce a device having a large surface area. Further, itrequires an expensive installation in its production line, thus leadingto a problem of a high cost, etc.

[0006] Under the circumstances, an organic electronic device has beenproposed wherein an organic semiconductor material is used for asemiconductor layer of an electronic device such as a field effecttransistor, a light emitting diode or a nonlinear optical device.According to such a proposal, such a semiconductor layer can be preparedby a relatively low temperature process, whereby a plastic film can beused as the substrate, and there is a merit such that a device which islight in weight, excellent in flexibility and scarcely breakable, can beprepared. Further, it can be formed by a coating method or a printingmethod, whereby there is a merit such that a device having a large areacan be produced at low cost without necessity of an expensiveinstallation. Further, the organic material is rich in variation, and itis possible to basically change the properties of the material bychanging its molecular structure, whereby there is a possibility that itis possible to obtain a device having a function which an inorganicmaterial can not provide.

[0007] Organic semiconductor materials may be classified broadly intotwo types i.e. high molecular compound material (a polymer material) andlow molecular compound material. With respect to each of them, there isa report i.e. on a device employing a conductive high molecular compoundor a conjugated high molecular compound (JP-A-61-202467), or on a deviceemploying a low molecular compound (JP2984370).

[0008] As such a high molecular compound material, a conductive polymeror a conjugated polymer is, for example, typical, and it has beenattempted to use a conjugated polymer compound as it is, as asemiconductor, or to carry out switching by applying an electric fieldto introduce or withdraw ions (dopants) to or from a conjugated polymercompound. However, there have been problems inherent to a polymer, suchthat the solubility in a solvent is low, whereby a uniform coating fluidcan hardly be obtained, the film is poor in uniformity or stability,defects attributable to incomplete structural portions are likely toresult during the film formation, the purification is difficult, and theoxidation potential tends to be low, whereby the material is susceptibleto oxidation. Thus, a material having high performance and highstability has not yet been found.

[0009] Whereas, in the case of the low molecular compound, the structureof the compound obtainable as a result of the synthesis is substantiallypredetermined, and various purification methods such as sublimationpurification, recrystallization, column chromatography, etc. can beused. Thus, it is superior in that the purity is high, and a materialhaving high performance and high stability can readily be obtainable.

[0010] As an example of such a low molecular compound material, anaromatic condensed hydrocarbon compound such as pentacene or anoligothiophene having 4 or more thiophene rings chained, which as formedinto a film by vapor deposition, shows a mobility as high as amorphoussilicon (a-Si), has been reported. However, such a low molecularcompound tends to be oxidized although not so much as the high molecularweight compound, and there is a problem from the viewpoint of thestability. Namely, oxygen in the air is likely to be doped to theorganic semiconductor film, whereby it is likely that the carrierdensity increases, and the leakage current increases or the mobilitychanges, whereby constant characteristics can hardly be obtainable.

[0011] Further, the low molecular compound can hardly be one whereby thecharacteristics of an organic compound are sufficiently utilized, sincea coating process is hardly applicable thereto, and it is required toemploy a film-forming method by vapor deposition which makes theproduction cost high. Further, if the low molecular weight compound isformed into a film by coating of its solution, a uniform film can hardlybe obtainable, since it will have a granular structure bycrystallization, and thus, there will be many cases wherein there is aproblem in the film forming properties.

[0012] For example, applications of phthalocyanines to field effecttransistors have been reported (JP-A-11-251601, JP-A-2000-174277, Appl.Phys. Lett., vol. 69 (1996), p. 3,086). However, phthalocyanines areusually insoluble in solvents, to prepare such devices, and it isnecessary to carry out film formation by a vacuum vapor depositionmethod.

[0013] Under the circumstances, methods have been reported in recentyears wherein a precursor for a low molecular compound having a highsolubility in a solvent, is dissolved in a solvent or the like, thenformed into a film by a coating process and then converted to asemiconductor to obtain an organic semiconductor film, so that a fieldeffective transistor is thereby prepared. For example, there are caseswherein pentacene or analogous aromatic hydrocarbons are employed(Science, vol. 270 (1995) p. 972, Optical Materials vol. 12 (1999), p.189, J. Appln. Phys. Vol. 79 (1996) p. 2,136).

[0014] Here, the operation characteristics of a field effect transistorare determined mainly by the carrier mobility μ or electroconductivityof the semiconductor layer, the capacitance Ci of the insulating layer,and the construction of the device (such as the source•drain electrodedistance L and width W, the thickness d of the insulating layer, etc.).Among them, it is important that the carrier mobility μ (hereinaftersometimes referred to simply as the mobility) of the semiconductormaterial to be used for the semiconductor layer, is high. With respectto pentacene, a case where the mobility is 0.2 cm²/Vs depending upon thecondition of the film, has been reported. However, the mobilitydemonstrated by an actual application to a device has been at a level of10⁻² cm²/Vs, and the mobility in the practical use is not yet high.Further, from the pentacene precursor in this case, a tetrachlorobenzenemolecule will be detached, but tetrachlorobenzene is not only hardlyremovable from the reaction system as the boiling point is high, butalso problematic in view of its toxicity.

[0015] Meanwhile, as a material for an optical device to obtain aphotoelectric current or photoelectromotive force, a porphyrin compoundhas been studied, and an application of benzoporphyrin to a solar cellis disclosed in JP-A-9-18039. However, its carrier mobility is low, andwhen the mobility is calculated from the carrier density and theresistivity disclosed in Examples, it is still at a level of 1.3×10⁻⁶cm²/Vs even at the maximum. Since the mobility is so low, the study onthe application of the porphyrin compound has been limited to an opticaldevice, and no application to an organic electronic device has beenobserved wherein all mobility or electromobility is positively utilized.

[0016] As described above, an organic semiconductor material has variouscharacteristics which are not observed with an inorganic semiconductormaterial. However, organic semiconductor materials having relativelyhigh performance, such as phthalocyanines, pentacenes oroligothiophenes, are all restricted in that the process for theirproduction has been limited to a vapor deposition process which ishighly costly. Therefore, it is desired to obtain an organic electronicdevice which can be produced by a simpler process and which, at the sametime, has practical characteristics.

[0017] Accordingly, an organic semiconductor material which has highcarrier mobility and stability and which can be formed into a film by asimple production process such as a coating process, and an organicelectronic device employing such an organic semiconductor material, havebeen desired.

SUMMARY OF THE INVENTION

[0018] As a result of various studies made under the abovecircumstances, it has been found that an organic electronic deviceemploying, as a semiconductor material, a compound having a certainspecific porphyrin skeleton, is useful, and the present invention hasbeen accomplished on the basis of this discovery. With respect toporphyrin, an application to a solar cell has been known. However, inthat application, the mobility has been still inadequate, probablybecause purification of the porphyrin itself has been inadequate. Thus,heretofore, no attention has been drawn to a porphyrin compound as amaterial for an organic electronic device, since its synthesis orpurification has been difficult.

[0019] However, as a result of the study on the application of aporphyrin compound by the present inventors, it has been surprisinglyfound that a compound having a certain specific generalized porphyrinskeleton can be formed into a film even by a solution process and showsa high mobility, and it thus presents an advantageous performance ascompared with other organic semiconductor materials.

[0020] Namely, in a first aspect, the present invention provides anorganic semiconductor material comprising a compound which has ageneralized porphyrin skeleton and which has a molecular structure suchthat the distance from the generalized porphyrin ring plane to thecenter of each atom forming the generalized porphyrin skeleton, is notmore than 1 Å

[0021] In a second aspect, the present invention provides an organicsemiconductor material comprising a compound which has a generalizedporphyrin skeleton and which has a mobility of at least 1×10⁻⁵cm²/Vs.

[0022] In a third aspect, the present invention provides an organicelectronic device comprising a semiconductor layer and at least twoelectrodes, wherein the semiconductor layer contains the above organicsemiconductor material.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023]FIGS. 1A to 1D are schematic views showing field effecttransistors (FET) of the present invention.

[0024]FIG. 2 is a schematic view showing a static induction transistor(SIT) of the present invention.

[0025]FIGS. 3E and 3F are schematic views showing diode devices of thepresent invention.

[0026]FIG. 4 is a graph showing the results of a thermal analysis of theporphyrin compound obtained in Preparation Example 1.

[0027]FIG. 5 is a graph showing the IR spectrum of a film obtained bydrying a solution of the porphyrin compound (1) obtained in PreparationExample 1.

[0028]FIG. 6 is a graph showing the IR spectrum of a film obtained byfurther heating the film of FIG. 5 obtained in Preparation Example 1.

[0029]FIG. 7 is a graph showing the thin film absorption spectra beforeand after heating in Preparation Example 1.

[0030]FIG. 8 is a graph showing the results of the observation of theFET characteristics in Example 1.

[0031]FIG. 9 is a graph showing the X-ray diffraction patterns of thesemiconductor film in Example 5.

[0032]FIG. 10 is a graph showing the X-ray diffraction patterns of thesemiconductor films in Examples 5 and 6.

[0033]FIG. 11 is a graph showing the hysteresis of the drain current byscanning of the gate voltage, of the devices of Examples 6 and 7.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

[0034] Now, preferred embodiments of the present invention will bedescribed in detail.

[0035] Firstly, the organic semiconductor material of the presentinvention will be described. In the present invention, a compound havinga specific generalized porphyrin skeleton, is employed.

[0036] Compound having a Generalized Porphyrin Skeleton

[0037] In the present invention, the compound having a generalizedporphyrin skeleton is a general term for a compound having a porphyrinskeleton and a compound having an expanded porphyrin skeleton, which isan analogue having the number of pyrrole rings forming a porphyrinskeleton increased or having a pyrrole ring replaced by e.g. a thiophenering or a furan ring, and it is a concept including, for example,porphyrin type, thiaporphyrin type, dithiaporphyrin type, oxaporphyrintype, dioxaporphyrin type and thiaoxaporphyrin type compounds.

[0038] Specifically, in the present invention, the compound having ageneralized porphyrin skeleton, is a compound containing a structurerepresented by the following formula (A).

[0039] In the above formula, each of Y¹ to Y^(n) which are independentof one another, is a π-conjugated single ring of hydrocarbon ring orheterocyclic ring, and each of Y¹ to Y^(n) may be substituted. Each ofX¹ to X^(n) which are independent of one another, is a direct bond or aconnecting group consisting of a linear hydrocarbon group, and each ofX¹ to X^(n) may be substituted. Here, the symbol

represents a single bond or a double bond. n is an integer of from 4 to20. Further, in the structure represented by the above formula (A) as awhole, π-electron systems are conjugated in a ring form. Namely, thestructure represented by the above formula is a structure in whichπ-conjugated rings represented by Y¹ to Y^(n) are π-conjugated as awhole via X¹ to X^(n). Accordingly, each of Y¹ to Y^(n) is a planarunit, and the structure represented by the above formula (A) as a wholetakes a structure having a very high planar nature.

[0040] For an organic semiconductor material to have high carriermobility, it is desired that adjacent molecules well overlap each otherin a solid state. Namely, for a carrier i.e. an electron or a hole to betransmitted between molecules, interaction between π-electron orbitalsis important. It is well known that in an organic semiconductor,π-electrons play an important role for charge transport. However,substantially no case is known wherein π-electrons are conjugated to amacroscopic scale to show a semiconductor characteristic.

[0041] Particularly, in a molecular crystal, conjugation of π-electronsis limited within the molecule, and charge transport is done by themovement of an electric charge between molecules. In such a case, thegreater the overlapping of π-orbitals conjugated within the molecules,the higher the efficiency of the charge transport. Therefore, themobility of the molecular crystal will also have a directionaldependency. Further, this is reflected also to the fact that usually, ahighly crystalline material shows a higher mobility than an amorphousmaterial.

[0042] In order to increase the overlapping of π-orbitals amongmolecules, it is desired that the planar nature of π-conjugated systemsin the molecules, is high. As an index for the planar nature, thedeviation of atoms forming the generalized porphyrin skeleton, from thegeneralized porphyrin ring plane, may be employed.

[0043] Accordingly, the present invention is characterized in that thedistance from the generalized porphyrin ring plane to the center of eachatom forming the generalized porphyrin skeleton, is not more than 1 Å.If this distance is within 1 Å, the conditions to increase the mobilityand to provide a high planar nature, can be satisfied.

[0044] Here, “a generalized porphyrin ring” means a structurerepresented by the formula (A) comprising π-conjugated rings representedby Y¹ to Y^(n) and X¹ to X^(n). “The generalized porphyrin ring planemeans a plane such that the sum of squares of the distances from thecenters of all atoms forming the generalized porphyrin ring, becomesminimum. Further, “the generalized porphyrin skeleton” includes, inaddition to atoms forming the generalized porphyrin ring, an atom oratomic group which is bonded to the generalized porphyrin ring and whichis restrained from free rotation by a thermal energy at a level of roomtemperature (i.e. 25° C.).

[0045] Here, “an atom or atomic group which is bonded to the generalizedporphyrin ring and which is restrained from free rotation by a thermalenergy at a level of room temperature” means a case where the energybarrier against internal rotation of the bond between an atom of thegeneralized porphyrin ring and an atom directly bonded thereto, islarger than the thermal energy at room temperature (usually 25° C.). Forexample, it is a case, where the energy barrier against internalrotation is at least 10 kcal/mol.

[0046] Usually, the energy required for rotation of a bond can beobtained by actual measurement, but can also be obtained by calculationby e.g. a molecular orbital method. A non-empirical molecular orbitalmethod such as 6-311G (dp), or a semi-empirical molecular orbital methodsuch as MOPAC, may be employed. Each has its own merit, i.e. by thenon-empirical molecular orbital method, the precision is good, and bythe semi-empirical molecular orbital method, the calculation isrelatively simple.

[0047] In a case where two or more generalized porphyrin rings which canbe rotated freely each other are contained in one molecule, it is onlyrequired that the planar nature of each generalized porphyrin ring isgood, and it is not required to take such a structure that the pluralityof porphyrin skeletons contained in one molecule are in the same plane.

[0048] Now, the compound having a generalized porphyrin skeleton of thepresent invention will be described in further detail.

[0049] In the present invention, the compound having a generalizedporphyrin skeleton means a compound containing a structure representedby the following formula (A):

[0050] In the above formula, each of Y¹ to Y^(n) which are independentof one another, is a π-conjugated single ring of hydrocarbon ring orheterocyclic ring, and each of Y¹ to Y^(n) may be substituted. Each ofX¹ to X^(n) which are independent of one another, is a direct bond or aconnecting group consisting of a linear hydrocarbon group, and each ofX¹ to X^(n) may be substituted. Here, the symbol

represents a single bond or a double bond. n is an integer of from 4 to20. Further, in the structure represented by the above formula (A) as awhole, π-electron systems are conjugated in a ring form.

[0051] Preferably, n is an integer of from 4 to 10, more preferably, nis an integer of from 4 to 6, and most preferably, n is 4. n representsthe number of π-conjugated rings Y in the above structure, but if n istoo large, the planar nature tends to deteriorate, the electricalproperties tend to deteriorate, and the synthesis tends to be difficult.

[0052] In the above formula (A), each of Y¹ to Y^(n) which areindependent of one another, is a π-conjugated single ring of hydrocarbonring or heterocyclic ring group, and each of Y¹ to Y^(n) may have asubstituent, but is preferably a 5- to 8-membered single ring. It ismore preferably a 5- or 6-membered ring. Further preferably, it is a5-membered ring.

[0053] Preferred specific examples for Y¹ to Y^(n) will be shown below,but Y¹ to Y^(n) are not limited thereto. A 5-membered ring may, forexample, be a pyrrole ring, a thiophene ring, a furan ring, a thiazolering, a dithiazole ring, an oxazole ring, an oxadiazole ring, aselenophene ring or a cyclopentadiene ring. A 6-membered ring may, forexample, be a benzene ring, a pyridine ring, a pyrimidine ring, anaphthalene ring, an anthracene ring or a pyrene ring.

[0054] Each of Y¹ to Y^(n) may have a substituent. For example, each ofY¹ to Y^(n) may be condensed with another hydrocarbon ring orheterocyclic ring to form a condensed ring. Such another ring ispreferably an aromatic ring, whereby the planar nature will beincreased. Further, such another ring is preferably a 5- to 8-memberedring, more preferably a 5- or 6-membered ring.

[0055] Hereinafter, the single rings of Y¹ to Y^(n) or the condensedrings made of Y¹ to Y^(n) and another ring, will be generally referredto as rings containing Y¹ to Y^(n). Each of rings containing Y¹ to Y^(n)is preferably a single ring or a 2- to 8-condensed ring, more preferablya single ring or a 2- to 6-condensed ring, most preferably a single ringor a 2- to 4-condensed ring. It is particularly preferred that all ringscontaining Y¹ to Y^(n) are aromatic rings, whereby the planar naturewill be increased.

[0056] A preferred example of such another ring is a π-conjugated ringsuch as benzene, naphthalene, anthracene, pyridine or quinoline. Thecondensed ring made of Y¹ to Y^(n) and another ring may specifically be,for example, a benzopyrrole ring, a benzothiophene ring or a benzofuranring.

[0057] On the other hand, an undesirable example of such another ring istypically a bicyclo ring.

[0058] The rings containing Y¹ to Y^(n) may have substituents. Thefollowing groups may be mentioned as specific examples of thesubstituents which the rings containing Y¹ to Y^(n) may have:

[0059] A C₁₋₁₈ linear or branched alkyl group which may be substituted,such as a methyl group, an ethyl group, a propyl group, an isopropylgroup, a n-butyl group, a sec-butyl group, a tert-butyl group or an-heptyl group; a C₃₋₁₈ cyclic alkyl group which may be substituted,such as a cyclopropyl group, a cyclpentyl group, a cyclohexyl group oran adamantyl group; a C₂₋₁₈ linear or branched alkenyl group which maybe substituted, such as a vinyl group, a propenyl group or a hexenylgroup; a C₃₋₁₈ cyclic alkenyl group which may be substituted, such as acyclopentenyl group or a cyclohexenyl group; a C₂₋₁₈ linear or branchedalkynyl group which may be substituted, such as a propynyl group or ahexynyl group; a heterocyclic group which may be substituted, such as a2-thienyl group, a 2-pyridyl group, a 4-piperidyl group or a morpholinogroup; a C₆₋₁₈ aryl group which may be substituted, such as a phenylgroup, a tolyl group, a xylyl group or a mesityl group; a C₇₋₂₀ aralkylgroup which may be substituted, such as a benzyl group or a phenethylgroup; a C₁₋₁₈ linear or branched alkoxy group which may be substituted,such as a methoxy group, an ethoxy group, a n-propoxy group, anisopropoxy group, a n-butoxy group, a sec-butoxy group or a tert-butoxygroup; a C₃₋₁₈ linear or branched alkenyloxy group which may besubstituted, such as a propenyloxy group, a butenyloxy group or apentenyloxy group; and a C₁₋₁₈ linear or branched alkylthio group(mercapto group) which may be substituted, such as a methylthio group,an ethylthio group, a n-propylthio group, a n-butylthio group, asec-butylthio group or a tert-butylthio group.

[0060] Other specific examples may, for example, be a halogen atom suchas a fluorine atom, a chlorine atom or a bromine atom; a nitro group; anitroso group; a cyano group; an isocyano group; a cyanate group; anisocyanate group; a thiocyanate group; an isothiocyanate group; amercapto group; a hydroxy group; a hydroxyamino group; a formyl group; asulfonate group; a carboxyl group; an acyl group represented by —COR⁶,an amino group represented by —NR⁷R⁸, an acylamino group represented by—NHCOR⁹, a carbamate group represented by —NHCOOR¹⁰, a carboxylate grouprepresented by —COOR¹¹, an acyloxy group represented by —OCOR¹², acarbamoyl group represented by —CONR¹³R¹⁴, a sulfonyl group representedby —SO₂R¹⁵, a sulfamoyl group represented by —SO₂NR¹⁶R¹⁷, a sulfonategroup represented by —SO₃R¹⁸, a sulfoneamide group represented by—NHSO₂R¹⁹, and a sulfinyl group represented by —SOR²⁰. Here, each of R⁶,R⁹, R¹⁰, R¹¹, R¹², R¹⁵, R¹⁸, R¹⁹ and R²⁰ is a hydrocarbon group whichmay be substituted, or a heterocyclic group which may be substituted,and each of R⁷, R⁸, R¹³ , R¹⁴ , R¹⁶ and R¹⁷ is a hydrogen atom, ahydrocarbon group which may be substituted or a heterocyclic group whichmay be substituted.

[0061] The hydrocarbon group represented by each of R⁶ to R²⁰ is alinear or branched alkyl group, a cyclic alkyl group, a linear orbranched alkenyl group, a cyclic alkenyl group, an aralkyl group or anaryl group. It is preferably a C₁₋₁₈ linear or branched alkyl group suchas a methyl group, an ethyl group, a propyl group, an isopropyl group, an-butyl group, a sec-butyl group, a tert-butyl group or a n-heptylgroup, a C₃₋₁₈ cyclic alkyl group such as a cyclopropyl group, acyclopentyl group, a cyclohexyl group or an adamantyl group, a C₂₋₁₈linear or branched alkenyl group such as a vinyl group, a propenyl groupor a hexenyl group, a C₃₋₁₈ cyclic alkenyl group such as a cyclopentenylgroup or a cyclohexenyl group, a C₇₋₂₀ aralkyl group such as a benzylgroup or a phenethyl group, or a C₆₋₁₈ aryl group such as a phenylgroup, a tolyl group, a xylyl group or a mesityl group. The aryl groupmoiety of such a group may further be substituted by the samesubstituent as for the above-described rings containing Y¹ to Y^(n).

[0062] The heterocyclic group represented by each of R⁶ to R²⁰ may, forexample, be a saturated heterocyclic group such as a 4-piperidyl group,a morpholino group, a 2-morpholinyl group or a piperazyl group, or anaromatic heterocyclic group such as a 2-furyl group, a 2-pyridyl group,a 2-thiazolyl group or a 2-quinolyl group. Such a group may contain aplurality of hetero atoms and may further have a substituent at anyposition. One having a preferred structure as the heterocyclic ring, isa 5- or 6-membered saturated heterocyclic ring or an aromaticheterocyclic ring which is a 5- or 6-membered single ring or a condensedring composed of two such 5- or 6-membered rings.

[0063] The linear or branched alkyl group, the cyclic alkyl group, thelinear or branched alkenyl group, the cyclic alkenyl group, the linearor branched alkynyl group, the linear or branched alkoxy group, or thelinear or branched alkylthio group, which the above-mentioned ringscontaining Y¹ to Y^(n) may have, and the alkyl chain moiety of the alkylgroup represented by each of R⁶ to R²⁰, may further have a substituent,and such a substituent may, for example, be as follows. A C₁₋₁₀ alkoxygroup such as a methoxy group, an ethoxy group, a n-propoxy group, anisopropoxy group, a n-butoxy group, a sec-butoxy group or a tert-butoxygroup; a C₂₋₁₂ alkoxyalkoxy group such as a methoxymethoxy group, anethoxymethoxy group, a propoxymethoxy group, an ethoxyethoxy group, apropoxyethoxy group or a methoxybutoxy group; a C₃₋₁₅ alkoxyalkoxyalkoxygroup such as a methoxymethoxymethoxy group, a methoxymethoxyethoxygroup, a methoxyethoxymethoxy group, a methoxymethoxyethoxy group or anethoxyethoxymethoxy group; a C₆₋₁₂ aryl group such as a phenyl group, atolyl group or a xylyl group (which may be further substituted by anoptional substituent); a C₆₋₁₂ aryloxy group such as a phenoxy group, atolyloxy group, a xylyloxy group or a naphthyloxy group; and a C₂₋₁₂alkenyloxy group such as an allyloxy group or a vinyloxy group.

[0064] Further, other substituents may, for example, be a heterocyclicgroup such as a 2-thienyl group, a 2-pyridyl group, a 4-piperidyl groupor a morpholino group; a cyano group; a nitro group; a hydroxyl group;an amino group; a C₁₋₁₀ alkylamino group such as an N,N-dimethylaminogroup or an N,N-diethylamino group; a C₁₋₆ alkylsulfonylamino group suchas a methylsulfonylamino group, an ethylsulfonylamino group or an-propylsulfonylamino group; a halogen atom such as a fluorine atom, achlorine atom or a bromine atom; a C₂₋₇ alkoxycarbonyl group such as acarboxyl group, a methoxycarbonyl group, an ethoxycarbonyl group, an-propoxycarbonyl group, an isopropoxycarbonyl group or an-butoxycarbonyl group; a C₂₋₇ alkylcarbonyloxy group such as amethylcarbonyloxy group, an ethylcarbonyloxy group, an-propylcarbonyloxy group, an isopropylcarbonyloxy group or an-butylcarbonyloxy group; and a C₂₋₇ alkoxycarbonyloxy group such as amethoxycarbonyloxy group, an ethoxycarbonyloxy group, an-propoxycarbonyloxy group, an isopropoxycarbonyloxy group or an-butoxycarbonyloxy group.

[0065] Preferred among the substituents which the rings containing Y¹ toY^(n) may have, may, for example, be a hydroxyl group, a C₁₋₁₀ alkyl,alkoxy, mercapto or acyl group, which may be substituted, a carboxylgroup or its ester with a C₁₋₁₀ alcohol, a formyl group, a carbamoylgroup, a halogen atom such as fluorine, chlorine, bromine or iodine, anamino group which may be substituted by a C₁₋₁₀ alkyl group, or a nitrogroup. Such a preferred group may further have a substituent. Forexample, an alkyl moiety of such a substituent may further besubstituted by a single atom such as a halogen atom.

[0066] Most preferably, each of rings containing Y¹ to Y^(n) isunsubstituted or has a substituent composed of a single atom such as ahalogen atom.

[0067] Each of X¹ to X^(n) which are independent of one another, is adirect bond or a connecting group consisting of a linear hydrocarbongroup, and each of X¹ to X^(n) may be substituted. The linearhydrocarbon group is preferably one having from 1 to 10 carbon atoms,more preferably from 1 to 5 carbon atoms. More preferably, it is a C₁₋₃unsaturated linear hydrocarbon group, particularly preferably, analkenylene group, an alkynylene group, an alkanediylidene group or analkenediylidene group.

[0068] Preferred specific examples for X¹ to X^(n) include a methinegroup, a vinylene group (an ethenylene group), an ethynylene group and(═C═C═), but are not limited thereto. Further, each may have asubstituent, although such a substituent is omitted in the aboveexamples.

[0069] Specific examples of the substituents which X¹ to X^(n) may have,may be roughly the same as the substituents which the rings containingY¹ to Y^(n) may have. However, bulky substituents which hinder freerotation, are undesirable. Preferred substituents may be a linear alkylgroup which may be substituted, a linear alkoxy group, a linear mercaptogroup, an ester of a carboxyl group with a C₁₋₁₀ alcohol, or a halogenatom. The substituents which X¹ to X^(n) may have, may be bonded to eachother to form a ring.

[0070] Particularly preferred among them may be an unsubstituted linearalkyl group, a linear alkoxy group, a linear alkylthio group, an esterof a carboxyl group with a C₁₋₁₀ linear alcohol, or a halogen atom.

[0071] Most preferably, X¹ to X^(n) are unsubstituted or have asubstituent composed of a single atom such as a halogen atom.

[0072] On the other hand, a typical example of an undesirablesubstituent is a phenyl group.

[0073] Further, in the structure represented by the formula (A) as awhole, it is necessary that π-electron systems are conjugated in a ringform.

[0074] Further, the compound having a generalized porphyrin skeleton ofthe present invention, may have various metals, cations, anions, salts,etc., coordinated to some or all of Y¹ to Y^(n) in the above structure.For example, a bivalent metal atom may be mentioned, and specificexamples include Zn, Cu, Fe, Ni and Co. Further, an atomic group havinga trivalent or higher valent metal and another atom bonded, such asFe—B¹, Al—B², Ti═O or Si—B³B⁴, may, for example, be mentioned. Here,each of B¹, B², B³ and B⁴ is a monovalent group such as a halogen atom,an alkyl group or an alkoxy group.

[0075] Examples of such porphyrin type and expanded porphyrin typecompounds are disclosed, for example, in THE PORPHYRIN HANDBOOK, VOL.1-10, ACADEMIC PRESS (2000), edited by KARL M. KADISH KEVIN, M. SMITHROGER GUILARD.

[0076] Further, it may be one wherein the same or different twogeneralized porphyrin rings are commonly conjugated to one atom, onewherein the same or different two generalized porphyrin rings are bondedvia at least one atom or atomic group, or one wherein the same ordifferent at least three generalized porphyrin rings are bonded in theform of a long chain.

[0077] As the compound having a generalized porphyrin skeleton of thepresent invention, most preferred is specifically one containing astructure represented by the following formula (1) or (2).

[0078] In the above formulae (1) and (2), each of Z^(ia) and Z^(ib) (i=1to 4) represents a monovalent organic group, and Z^(ia) and Z^(ib) maybe bonded to form a ring. The monovalent organic group may, for example,be a hydrogen atom, a hydroxyl group, a C₁₋₁₀ alkyl group which may besubstituted, an alkoxy group, a mercapto group, an acyl group, acarboxyl group or its ester with a C₁₋₁₀ alcohol, a formyl group, acarbamoyl group, a halogen atom such as fluorine, chlorine, bromine oriodine, an amino group which may be substituted by a C₁₋₁₀ alkyl group,or a nitro group, and such a group may further have a substituent.Further, as an example of the organic group wherein Z^(ia) and Z^(ib)are bonded to form a ring, the ring formed by the structureZ^(ia)-CH═CH-Z^(ib), may, for example, be an aromatic hydrocarbon suchas a benzene ring, a naphthalene ring or an anthracene ring, aheterocyclic ring such as a pyridine ring, a quinoline ring, a furanring or a thiophene ring, or a non-aromatic cyclic hydrocarbon such as acyclohexene. Further, each of R¹ to R⁴ is a hydrogen atom or amonovalent organic group. Such an organic group may, for example, be analkyl group which may be substituted, an aryl group, an alkoxy group, amercapto group, an ester of a carboxyl group with a C₁₋₁₀ alcohol, or ahalogen atom.

[0079] Further, M is a bivalent metal atom, such as Zn, Cu, Fe, Ni orCo, or an atomic group having a trivalent or higher valent metal andanother atom bonded, such as Fe—B¹, Al—B², Ti═O or Si—B³B⁴. Here, eachof B¹, B², B³ and B⁴ is a monovalent group such as a halogen atom, analkyl group or an alkoxy group.

[0080] Further, there may be one wherein two porphyrin rings arecommonly coordinated to one atom, one wherein two porphyrin rings arebonded via at least one atom or atomic group, or one wherein at leastthree such porphyrin rings are bonded in the form of a long chain.

[0081] As mentioned above, in order to increase overlapping of theπ-orbitals between molecules, the porphyrin compound of the presentinvention is preferably one wherein the planar nature of theπ-conjugated systems in the molecule is high, and it is characterized inthat it has a molecular structure wherein the distance from theporphyrin ring plane to the center of each atom forming the porphyrinskeleton, is not more than 1 Å. The atoms forming the porphyrin skeletoninclude, in addition to atoms forming the porphyrin ring, an atom oratomic group which is bonded to a substituent Z^(ia), Z^(ib) or R¹ to R⁴of (1) or (2), and free rotation of which by a thermal energy at a levelof room temperature is restrained.

[0082] For example, carbon atoms forming four benzene rings or atetraphenylporphyrin having the benzene rings bonded at four mesopositions of a porphyrin ring, are restrained from free rotation due tosteric hindrance between the benzene rings and the porphyrin ring, andthus, they are included in the porphyrin skeleton. It is not desirablethat such groups are present at positions deviated from the plane of theporphyrin ring, since they tend to hinder overlapping of porphyrin ringsby the steric hindrance. On the other hand, in a case where rotation ofthe bond is free as in the case of an alkyl group or an alkoxy group,especially a linear alkyl group or a linear alkoxy group, the structurecan freely be adjusted so that the porphyrin rings can be overlapped,and such a group will not be a hindrance and therefore is not includedin the porphyrin skeleton.

[0083] The porphyrin ring plane can be defined as such a plane that thesum of squares of the distances from the centers of all atoms formingthe porphyrin ring, would be minimum. If the distance from this plane tothe centers of atoms forming the porphyrin skeleton, is within 1 Å, itis possible to satisfy the conditions that the planar nature is high,and the mobility is high.

[0084] As typical examples of the generalized porphyrin compound nothaving a high planar nature, the following tetraphenylporphyrin, whichis most well known as a porphyrin, and a porphyrin including bicyclostructure may be mentioned.

[0085] Accordingly, Z^(ia) or Z^(ib) in the above formula (1) or (2) ispreferably a single atom such as a hydrogen atom or a halogen atom.Further, it may also be preferably a group forming a ring having a highplanar nature and having no substituent, particularly one wherein atleast one of Z^(ia)—CH═CH-Z^(ib) (i=1 to 4) is a group forming anaromatic ring such as benzene, naphthalene or anthracene, or one whereinall of Z^(ia)-CH═CH-Z^(ib) (i=1 to 4) are aromatic rings. Further, eachof R¹ to R⁴ is preferably a single atom such as a hydrogen atom or ahalogen atom.

[0086] In the present invention, the organic semiconductor material isalso characterized in that it comprises a compound which has ageneralized porphyrin skeleton and which has a carrier mobility(mobility: μ) of at least 1×10⁻⁵ cm²/Vs.

[0087] The carrier mobility required for application to an electronicdevice is determined from the degree of the electric current to becontrolled, the switching speed and the structure of the device. Byusing the generalized porphyrin compound of the present invention, it ispossible to provide an organic device having a carrier mobility of atleast 1×10⁻⁵ cm²/Vs, preferably at least 1×10⁻³ cm²/Vs. The mobility ofa conventional organic semiconductor of molecular crystal is at a levelof about 1 cm²/Vs with a single crystal of an aromatic condensedhydrocarbon such as pentacene. A porphyrin molecule has π-orbitals whichare substantially expanded, whereby there is a possibility that theinteraction between molecules can be increased, and further, a centermetal is present, whereby it can be expected to utilize the interactionvia the metal, and thus it is considered possible to accomplish amobility of from 10 cm²/Vs to 100 cm²/Vs.

[0088] The purity of the semiconductor material constituting thesemiconductor layer may be mentioned as another condition for the highmobility. An impurity which traps the carrier causes a substantialdeterioration of the mobility even in a trace amount. An impurity whichis likely to form such a trap, is one having a level to receive thecarrier in the energy gap of the semiconductor. When the carrier is ahole, it is one having the highest occupied molecular orbital (HOMO)level higher than the semiconductor, and when the carrier is anelectron, it is one having the lowest unoccupied molecular orbital(LUMO) level lower than the semiconductor.

[0089] Even an impurity which presents no such an energy level, willcause a deterioration of the mobility, if the concentration becomes highto bring about a defect in the crystal structure of the semiconductor.Accordingly, the concentration of impurities is desired to be low,preferably at most 10%, more preferably at most 1%. The process ofemploying a precursor having a high solubility, which will be describedhereinafter, has a merit in that it is thereby possible to form asemiconductor layer of high purity.

[0090] With a generalized porphyrin compound, a hole will usually be acarrier, but an electron may be made to be a carrier, as electrontransport properties are provided by a substituent or by the centermetal.

[0091] In a case where injection of electric charge from an electrode isrequired to take place smoothly as in the case of a field effecttransistor, a preferred position is present for the energy level of thecarrier. In the case of a hole, if HOMO is too low, the barrier againstinjection of the electric charge tends to be substantial, such beingundesirable. On the other hand, if HOMO is too high, the material tendsto be susceptible to oxidation by the air and tends to be unstable.Accordingly, the ionization potential in the solid state correspondingto the HOMO level is preferably at most 5.6 eV, more preferably at most5.3 eV. Further, the ionization potential is preferably at least 4.5 eV,more preferably at least 4.8 eV.

[0092] The compound having a generalized porphyrin skeleton of thepresent invention is preferably in a solid state at room temperature forapplication to a device. Depending upon the substituent in the formula(1) or (2), a compound showing a liquid crystal property can beobtained, and it can be used as an organic semiconductor even in aliquid crystal state. Especially, the generalized porphyrin compound ofthe present invention has a structure having a good planar nature,whereby it is expected that a discotic liquid crystal may be obtained,and such a structure is suitable for transport of a carrier. It is notdesirable that a substantial change in the properties will take placewithin the operational temperature range. Accordingly, a compound ispreferred, of which the phase transfer temperature such as a meltingpoint or a solidification point is not within a range of from 5° C. to40° C. The compound which is in a solid state at room temperature ispreferably such that the melting point or the glass transition point isat least 50° C., more preferably at least 100° C.

[0093] Further, the ON/OFF ratio of the organic semiconductor materialcomprising the generalized porphyrin compound of the present inventionis desirably as high as possible, preferably at least 800, morepreferably at least 1,000.

[0094] Now, examples of preferred generalized porphyrin compounds of thepresent invention will be given. Here, structures containing no metalare exemplified. However, metal salts corresponding to the followingexamples or the corresponding molecules having substituents may likewisebe used as preferred examples. Further, molecular structures having goodsymmetry are mainly exemplified, but asymmetrical structures by acombination of partial structures, can also be used. The porphyrincompounds of the present invention are, of course, not limited to theseexemplified compounds.

[0095] Synthesis of the Generalized Porphyrin Compound

[0096] The generalized porphyrin compound of the present invention canbe synthesized by using the corresponding pyrrole compound, thiophenecompound, furan compound or the like, as the starting material. For thesynthesis of the generalized porphyrin compound, a method disclosed inTHE PORPHYRIN HANDBOOK, VOL. 1, ACADEMIC PRESS (2000), edited by KARL M.KADIS H KEVIN M. SMITH ROGER GUILARD, may, for example, be used.

[0097] For example, condensation of pyrrole and an aldehyde, isfrequently used particularly as a synthesis of a tetraphenylporphyrin.

[0098] In the above formula, Q¹ and Q² correspond to Z^(ia) and Z^(ib)in the formula (1) or (2), and Q³ corresponds to R¹ to R⁴.

[0099] Further, it can be obtained also by a condensation reaction of apyrrole having a carboxylate or a methyl group at the α-position.

[0100] In the above formulae, Q¹ and Q² correspond to Z^(ia) and Z^(ib)in the formula (1) or (2), and R⁵ is an alkyl group.

[0101] Among generalized porphyrin compounds of the present invention, abenzoporphyrin having a benzene ring condensed to at least one pyrrolering, thiophene ring or furan ring, can be prepared by using as itsprecursor, the corresponding bicyclo compound. Such a precursor is notof a planar structure, and thus, it has a high solubility in a solventand is hardly crystallizable and thus can be coated from a solution topresent an amorphous or substantially amorphous good film. This film maybe heat-treated for ethylene removal reaction to obtain a generalizedbenzoporphyrin film having a high planar nature. In the case of a nonsubstituted non-metal structure, the reaction may be represented by thefollowing chemical reaction. This reaction proceeds quantitatively byheating at a temperature of at least 100° C., preferably at least 150°C. Further, what is detached is an ethylene molecule, which willscarcely remain in the system, so that there will be no problem from theviewpoint of the toxicity or safety. Now, an example of atetrabenzoporphyrin having four benzene rings condensed, will be shown.

[0102] The following route may, for example, be mentioned as a synthesisof this bicyclo compound.

[0103] Here, the synthesis route up to the preparation of the pyrroleintermediate, may be replaced by another route, as follows.

[0104] A metal complex of this precursor can be obtained by mixing thiscompound with a metal salt in an organic solvent capable of dissolvingthem. The metal salt may be any salt so long as it is soluble in theorganic solvent, but an acetate is a typical example. The solvent may beany solvent so long as it is capable of dissolving the metal salt andthe bicyclo compound, but a preferred example may be chloroform, analcohol, dimethylformamide, tetrahydrofuran, acetonitrile,N-methylpyrrolidone, or a solvent mixture thereof.

[0105] Types of Devices

[0106] (1) Definition of Electronic Device

[0107] The electronic device of the present invention is a device havingat least two electrodes and designed to control the electric currentflowing between the electrodes or the resulting voltage by other thanlight, for example by electricity, magnetism or chemical substance. Itmay, for example, be a device for controlling an electric current orvoltage by an application of a voltage, a device for controlling avoltage or electric current by an application of a magnetic field, or adevice for controlling a voltage or electric current by the action of achemical substance. Such control may, for example, be rectification,switching, amplification or oscillation. The corresponding devicespresently practically realized by silicon or the like, include aresistor, a rectifier (a diode), a switching device (a transistor or athyristor), an amplification device (a transistor), a memory device, achemical sensor, and a combination of these devices, and an integrateddevice. The generalized porphyrin compound of the present invention hasa high carrier mobility μ, whereby it is highly effective when appliedto a switching device (a transistor or a thyristor).

[0108] Further, even a device to be controlled by light or to controlemission of light may be included for an application other than anoperation in which the generalized porphyrin material directly absorbslight or emits light, for example a device to be used for wiring or forcontrol of the above voltage or electric current.

[0109] More specific examples of the electronic device may be thosedisclosed in Physics of Semiconductor Devices, 2nd Edition(Wiley-Interscience 1981) edited by S. M. Sze.

[0110] (2) Field Effect Transistor

[0111] As an example of an organic device of the present invention, afield effect transistor (FET) may be mentioned. This comprises twoelectrodes (a source electrode and a drain electrode) in contact withthe semiconductor, and an electric current flowing between theelectrodes (so-called a channel), is controlled by a voltage applied toanother electrode so called a gate. The gate electrode is constructedmerely to apply an electric field to the semiconductor layer, whereby anelectric current will not basically flow, and it is called a fieldeffect transistor.

[0112] According to the present invention, the organic semiconductormaterial is employed, and accordingly, it can be prepared by a processat a relatively low temperature, whereby a plastic film may be used asthe substrate, and there is a merit in that a device which is light inweight, excellent in flexibility and scarcely breakable, can beprepared. Thus, it is possible to produce a field effect transistorhaving a thin film and being flexible, and such a transistor is used fora switching device for each cell, whereby an active matrix liquidcrystal display having flexibility can be prepared, and thus it iswidely applicable.

[0113] The operation characteristics of the field effect transistor aredetermined by e.g. the carrier mobility μ, the electroconductivity σ ofthe semiconductor layer, the capacitance Ci of the insulating layer, thestructure of the device (the distance L and the width W between thesource and drain electrodes, the thickness d of the insulating layer).As the semiconductor material to be used for the field effecttransistor, the higher the carrier mobility μ, the better. However, thegeneralized porphyrin compound of the present invention has acharacteristic that the carrier mobility μ is high, whereby when it isused for the field effect transistor, it is highly effective. Further,the field effect transistor of the present invention has a small leakcurrent, and the ON/OFF ratio is large, whereby there is a merit thatthe stability of the film and the properties is high, and the usefullife is long. Further, there are merits such that the useful temperaturewidth is wide, the film forming property is good, it can be applicableto a large area, and it can be produced at low cost.

[0114] It is common to employ a structure wherein the gate electrode isinsulated by an insulating film (Metal-Insulator-Semiconductor i.e. MISstructure). Further, there is a structure wherein a gate electrode isformed via a Schottkey barrier. However, in the case of FET employing anorganic semiconductor material, the MIS structure is commonly employed.

[0115] Now, the field effect transistor of the present invention will bedescribed in further detail with reference to the drawings, but thepresent invention is by no means restricted to such structures.

[0116] In FIGS. 1A to 1D, some structural examples of the field effecttransistor device are shown. Reference numeral 1 represents asemiconductor layer, 2 an insulator layer, 3 and 4 a source electrodeand a drain electrode, 5 a gate electrode, and 6 a substrate. Thedisposition of the respective layers and electrodes can be suitablyselected depending upon the application of the device. As the electriccurrent flows in a direction parallel to the substrate, the device iscalled a horizontal FET.

[0117] The substrate 6 is required to be such that each layer formedthereon can be maintained without peeling. As such a material, aninsulating material, such as a sheet or film made of a resin, paper,glass or ceramics, one having an insulating layer formed by coating orthe like on a conductive substrate made of a metal or an alloy, acomposite material made of a combination of various types such as aresin and an inorganic material, may, for example, be mentioned. It ispreferred to employ a resin film or paper, since flexibility can beimparted to the device.

[0118] A material having an electrical conductivity is used for theelectrodes 3, 4 and 5. For example, a metal such as platinum, gold,aluminum, chromium, nickel, cobalt, copper, titanium, magnesium,calcium, barium or sodium, or an alloy containing them, anelectroconductive oxide such as InO₂, SnO₂ or ITO, an electroconductivepolymer compound such as polyaniline, polypyrrole, polythiophene,polyacetylene or polydiacetylene, a semiconductor such as silicon,germanium or gallium arsenide, or carbon material such as carbon black,fullerene, carbon nanotube or graphite, may, for example, be mentioned.Further, doping may be applied to the electroconductive polymer compoundor to a semiconductor. The dopant may, for example, be an acid such ashydrochloric acid, sulfuric acid or sulfonic acid, a Lewis acid such asPF₆, AsF₅ or FeCl₃, a halogen atom such as iodine, or a metal atom suchas sodium or potassium. Further, a conductive composite material havingcarbon black or metal particles dispersed to the above material, mayalso be employed.

[0119] Further, to the electrodes 3, 4 and 5, wirings not shown, areconnected, and such wirings may be made of substantially the samematerials as the electrodes.

[0120] For the insulating layer 2, a material having an insulatingproperty can be employed. For example, a polymer such as polymethylmethacrylate, polystyrene, polyvinylphenol, polyimide, polycarbonate,polyester, polyvinyl alcohol, polyvinyl acetate, polyurethane,polysulfone, an epoxy resin or a phenol resin, a copolymer prepared by acombination thereof, an oxide such as silicon dioxide, aluminum oxide ortitanium oxide, a ferroelectric oxide such as SrTiO₃ or BaTiO₃, anitride such as silicon nitride, a dielectric such as a sulfide orfluoride, or a polymer having such dielectric particles dispersedtherein, may be mentioned.

[0121] As mentioned above, the thickness of the insulating layer 2 ispreferably as thin as possible within a range where the necessaryfunctions can be obtained. Usually, the thickness is at least 1 nm,preferably at least 5 nm, more preferably at least 10 nm. However,usually, the thickness is at most 10 μm, preferably at most 1 μm, morepreferably at most 500 nm.

[0122] With respect to the material of the semiconductor layer 1, asemiconductor layer containing the above-mentioned generalized porphyrincompound as the main component, is preferably employed. The maincomponent means that it is contained in an amount of at least 50 wt %.More preferably, it is contained at least 80 wt %. In order to improvethe properties or to impart other properties, other organicsemiconductor materials may be mixed, or various additives may be added,as the case requires. Further, the semiconductor layer 1 may be composedof a plurality of layers.

[0123] The thickness of the semiconductor layer 1 is preferably as thinas possible within a range where the necessary functions can beobtained. In a horizontal field effect transistor device (a sourceelectrode and a drain electrode as disposed substantially horizontally)as shown in FIG. 1, the characteristics of the device are not dependenton the film thickness so long as the film thickness is at least aprescribed level. On the other hand, if the film thickness becomesthick, a leak current tends to increase. In order to obtain thenecessary functions, the film thickness is usually at least 1 nm,preferably at least 5 nm, more preferably at least 10 nm. However, thefilm thickness is usually at most 10 μm, preferably at most 1 μm, morepreferably at most 500 nm.

[0124] In an organic electronic device of the present invention, betweenthe respective layers, or on the outer surface of the device, anotherlayer may be provided, as the case requires. For example, a protectivelayer may be formed on the semiconductor layer directly or via anotherlayer, whereby there will be a merit such that the influence of theouter atmosphere such as moisture can be minimized. Further, there is amerit that the electrical characteristics can be stabilized, such thatthe ON/OFF ratio of the device is increased.

[0125] The material for the protective layer is not particularlylimited. For example, films made of various resins such as an epoxyresin, an acrylic resin such as polymethyl methacrylate, polyurethane,polyimide, polyvinyl alcohol, a fluorinated resin and polyolefin, orfilms made of dielectrics, such as inorganic oxide films or nitridefilms, of e.g. silicon oxide, aluminum oxide, or silicon nitride, maypreferably be mentioned. Particularly, a resin (polymer) having lowwater absorptivity or low permeability of oxygen or moisture, ispreferred.

[0126] Some of generalized porphyrin compounds may absorb light togenerate an electric charge. If necessary, the electronic device portionmay be shielded from light, for example, by forming a pattern (aso-called black matrix) having a low light transmittance at a desiredregion. For such a pattern, a film of a metal such as chromium,aluminum, silver or gold, a resin film having a pigment such as carbonblack dispersed therein, or a film of an organic dye, may, for example,be used.

[0127] (3) Static Induction Transistor (SIT)

[0128] A static induction transistor (SIT) may be mentioned as one typeof the field effect transistor. The structure of SIT will be described.

[0129] In horizontal FET, a source electrode and a drain electrode aredisposed on a substrate, and the current flowing direction isperpendicular to the electric field induced by the gate. Whereas, SIT ischaracterized in that at a proper position between a source electrodeand a drain electrode, a gate electrode is disposed in a grid pattern,and the current flowing direction is in parallel with the electric fieldinduced by the gate.

[0130]FIG. 2 is a schematic view showing a static induction transistor(SIT). Reference numeral 7 represents a source electrode, 8 a drainelectrode, 9 a gate electrode, and 10 a semiconductor layer. These areformed on a substrate not shown. According to this SIT structure, theflow of carriers will spread in a plane, whereby a large amount ofcarriers can be moved all at once. Further, the source electrode and thedrain electrode are arranged vertically, whereby the electrode spacingcan be minimized, and the response speed will be high. Accordingly, thisstructure can be preferably applied to an application where a largecurrent is conducted or switching is carried out at a high speed.

[0131] With respect to the semiconductor layer 10, the same descriptionas of the above semiconductor layer 1 applies, and with respect to theelectrodes 7 and 8, the same description as of the above electrodes 3, 4and 5 applies.

[0132] The gate electrode 9 has a network or stripe structure, so thatcarriers will pass through spacings of the network or stripe structure.The spacings of the network of the gate electrode are preferably smallerthan the distance between the source and the drain (which corresponds tothe thickness of the device). Further, the thickness of the electrode isusually at least 10 nm, preferably at least 20 nm. However, it isusually at most 10 μm, preferably at most 1 μm.

[0133] As the material for the gate electrode 9, the same material asfor the above-mentioned electrodes 3, 4 and 5 may be employed. However,preferably, an insular structured thin film made of a conductivematerial such as a metal, alloy or conductive polymer, is employed. Forexample, a semitransparent aluminum electrode in the form of a thin filmhaving a thickness of at most 50 nm may be employed.

[0134] Between the gate electrode 9 and the semiconductor layer 10, itis common to provide an insulating layer or an energy barrier to preventoutgoing or incoming of carriers to or from the electrode. For example,an insulating layer may be formed by patterning around the electrode.Otherwise, as the electrode material, a metal capable of forming anenergy barrier against a semiconductor may be selected to suppressoutgoing or incoming of carriers to or from the semiconductor layer. Forexample, by selecting aluminum, a so-called shot key barrier can beformed against a p-type semiconductor.

[0135] Further, between the respective layers or on the outer surface ofthe device, another layer may be formed as the case requires.

[0136] The static induction transistor of the present invention has suchmerits that the carrier mobility u is high, the leak current is small,the ON/OFF ratio is large, the stability of the film and the propertiesis high, and the useful life is long. Further, it has such merits thatthe useful temperature range is wide, the film forming property is good,it is applicable to a large area, and it can be produced at low cost.

[0137] (4) Diode Device

[0138] As another example, a diode device may be mentioned. This is atwo-terminal device having an asymmetrical structure. FIGS. 3E and 3Fare schematic views of diode devices. These devices are provided onsubstrates not shown.

[0139] The device of 3E has a structure wherein a semiconductor layer 13comprising the generalized porphyrin compound is sandwiched between twometal electrodes 11 and 12 having different work functions. With respectto the semiconductor layer 13, the same description as of the abovesemiconductor layer 1 applies. At least one of the electrodes 11 and 12forms an energy barrier against the semiconductor material. To form theenergy barrier, the electrodes and the semiconductor may be selected tohave different work functions. For example, as a metal to form an energybarrier against the p-type semiconductor, aluminum is often used. Asother electrode materials, the same ones as for the above-describedelectrodes 3, 4 and 5 may be employed, but preferred is a metal or analloy. When a voltage is applied to this device, so-called rectificationwill be observed, wherein the flowing current value varies dependingupon the polarity of the voltage. Accordingly, as an application of sucha diode device, a rectification device may be mentioned.

[0140] Whereas, the device shown in FIG. 3F has a structure in whichsemiconductor layers 16 and 17 having substantially different workfunctions, are sandwiched between electrodes 14 and 15. With respect tothe semiconductor layer 16, the same description as of the abovesemiconductor layer 1 applies. The semiconductor layer 17 may be made ofany material so long as its work function is substantially differentfrom the semiconductor layer 16, and as such a material, a perylenepigment, a phthalocyanine material, fullerene or a conjugated polymer,may, for example, be mentioned. With respect to the electrodes 14 and15, they may be made of the same material or different materials. Thesame materials as for the above electrodes 3, 4 and 5 may be employed.

[0141] Further, between the respective layers or on the outer surface ofthe device, another layer may be provided as the case requires.

[0142] (5) Resistance, etc.

[0143] Further, as another application, a resistant element may bementioned. This is a two-terminal element having a symmetrical structurein which a semiconductor layer formed on a substrate is sandwichedbetween two electrodes. The resistant element may be used as a resistorto adjust the resistance between the electrodes, or as a capacitor toadjust the capacitance between the electrodes by increasing theresistance.

[0144] With respect to the semiconductor layer, the same description asof the above semiconductor layer 1 applies, and with respect to theelectrodes, the same description as of the above electrodes 3, 4 and 5applies.

[0145] Further, between the respective layers or on the outer surface ofthe element, another layer may be provided, as the case requires.

[0146] Such a diode device or the resistance element will have a meritsuch that by using the organic semiconductor material of the presentinvention showing a high carrier mobility, the device parameter such asthe resistance value can be controlled widely, such is advantageous forintegration.

[0147] (6) Application of the Organic Electronic Device of the PresentInvention

[0148] (6-1) Active Matrix

[0149] The organic electronic device of the present invention can beused as a switching device of an active matrix of a display. Namely, byutilizing the ability to switch the electric current between the sourceand the drain by the voltage applied to the gate, the switch is put ononly when a voltage is applied or a current is supplied to a displaydevice, and during other time, the circuit is open, thereby to carry outhigh speed high contrast display.

[0150] As a display device to which the present invention is applicable,a liquid display device, a polymer-dispersed type liquid crystal displaydevice, an electrophoretic display device, an electroluminescent deviceor an electrocromic device may, for example, be mentioned.

[0151] Particularly, with the organic electronic device of the presentinvention, preparation of the device by a low temperature process ispossible, and it is possible to employ a substrate which is not durableagainst high temperature treatment, such as a plastic plate, a plasticfilm or paper. Further, preparation of the device by a coating orprinting process is possible, it is suitable for application to adisplay having a large area. Further, it is advantageous as a devicewhich makes an energy saving process or a low cost process possible, oras a substitute for a conventional active matrix.

[0152] (6-2) IC

[0153] Further, by integrating a transistor, a digital device or ananalogue device can be realized. As such an example, a logical circuitsuch as AND, OR, NAND or NOT, a memory device, an oscillation device oran amplification device may, for example, be mentioned. Further, by acombination thereof, an IC card or an IC tag may be prepared.

[0154] (6-3) Sensor

[0155] An organic semiconductor undergoes a substantial change in itsproperties by an external stimulus such as a gas, a chemical substanceor a temperature, and its application to a sensor is conceivable. Forexample, by measuring the amount of change in the properties of theorganic electronic device of the present invention by its contact with agas or a liquid, it is possible to detect chemical substances containedtherein quantitatively or qualitatively.

[0156] Process for Producing the Organic Electronic Device of thePresent Invention

[0157] A preferred process for producing the organic electronic deviceof the present invention will be described with reference to a case ofthe field effect transistor (FET) shown in FIG. 1A, but such a processis likewise applicable to other organic electronic devices.

[0158] (1) Substrate and Treatment of the Substrate

[0159] In general, an organic electronic device such as a field effecttransistor is prepared by providing a necessary layer and electrodes ona substrate 1. As the substrate, one described above can be employed.

[0160] In some cases, it is possible to improve the properties of thedevice by applying a prescribed surface treatment to the substrate. Forexample, by adjusting the degree of hydrophilicity/hydrophobicity of thesubstrate surface, the quality of the film to be formed thereon can beimproved. Especially, the properties of the organic semiconductormaterial will change substantially by the state of the film such asalignment of molecules, and by surface treatment of the substrate, it isconsidered possible to control the molecular alignment at theinterfacial portion between the substrate and the semiconductor film tobe formed thereon, thereby to improve the properties.

[0161] Such treatment of the substrate may, for example, be hydrophobictreatment with e.g. hexamethyldisilazane, cyclohexene or octadecyltrichlorosilane, acid treatment with e.g. hydrochloric acid, sulfuricacid or acetic acid, alkali treatment with e.g. sodium hydroxide,potassium hydroxide, calcium hydroxide or ammonia, ozone treatment,fluorination treatment, plasma treatment in e.g. oxygen or argon,treatment for forming a Langmuir•Blodgett film, treatment for forming athin film of other insulator or semiconductor, mechanical treatment, orelectric treatment such as corona discharge treatment.

[0162] (2) Formation of Electrodes

[0163] Then, a gate electrode 5 is formed. As the electrode material,the one described above can be employed.

[0164] To form an electrode film, known various methods may be employed,such as a vacuum vapor deposition method, a sputtering method, a coatingmethod, a printing method and a sol gel method.

[0165] After the film formation, patterning is carried out, as the caserequires to obtain a desired shape. Also for such patterning, knownvarious methods may be employed. For example, a photolithography methodin which patterning and etching (wet etching with an etching liquid, ordry etching by reactive plasma) of a photoresist are combined, aprinting method such as ink jet printing, screen printing, offsetprinting or relief printing, a soft lithography method such as amicrocontact printing method, and a method having a plurality of suchmethods combined, may be used. Further, a pattern may directly beprepared, for example, by irradiating energy rays such as laser orelectron rays to remove the material or to change theelectro-conductivity of the material.

[0166] (3) Insulating Layer

[0167] Then, an insulator layer 2 is formed. As the insulator material,the one described in the above (3) can be employed.

[0168] To form the insulator layer 2, known various methods may beemployed. For example, a coating method such as spin coating or bladecoating, a printing method such as screen printing or ink jet printing,a vacuum vapor deposition method, a sputtering method, or a method offorming an oxide film on a metal, such as alumite on aluminum, may beemployed.

[0169] In an embodiment wherein a semiconductor layer is formed on aninsulator layer, a prescribed surface treatment may be applied to theinsulator layer in order to have semiconductor molecules well aligned atthe interface of the two layers. The method for the surface treatmentmay be the same as used for the surface treatment of the substrate.

[0170] Further, a source electrode 3 and a drain electrode 4 are formed,but the forming method, etc. may be in accordance with those for thegate electrode 5.

[0171] (4) Semiconductor Layer

[0172] Then, an organic semiconductor layer 1 is formed. As the organicsemiconductor material, the one described above can be employed. To formthe semiconductor layer, known various methods may be employed. However,they may be generally classified into a method for forming by a vacuumprocess such as a sputtering method or a vapor deposition method, and amethod for forming by a solution process, such as a coating method or aprinting method.

[0173] (5) Vacuum Process

[0174] A method of forming an organic semiconductor material into a filmby a vacuum process to obtain an organic semiconductor layer, will bedescribed in detail. For example, a vacuum vapor deposition method maybe employed wherein the material is put into a crucible or a metal boatand heated in vacuum to evaporate it and to let it deposit on thesubstrate. At that time, the vacuum degree is usually at most 1×10⁻³Torr (1.3×10⁻¹ Pa), preferably at most 1×10⁻⁶ Torr (1.3×10⁻⁴ Pa).Further, depending upon the substrate temperature, the properties of thesemiconductor film, and accordingly, of the device, will change, andaccordingly, the optimum substrate temperature is selected. It isusually within a range of from 0° C. to 200° C. Further, the vapordeposition rate is usually at least 0.001 nm/sec, preferably at least0.01 nm/sec. However, it is usually at most 10 nm/sec, preferably atmost 1 nm/sec. Instead of the method of heating and evaporating thematerial, a sputtering method may be employed wherein accelerated ionsof e.g. argon are impinged to the material target to drive out thematerial atoms and to let them deposit on the substrate.

[0175] The organic semiconductor material of the present invention is arelatively low molecular compound. Accordingly, such a vacuum processcan be employed. The vacuum process requires an expensive installationbut has a merit such that the film forming performance is good, and auniform film can readily be obtained.

[0176] (6) Solution Process

[0177] A method of forming an organic semiconductor material into a filmby a solution process thereby to obtain an organic semiconductor layer,will be described in detail. Firstly, the organic semiconductor materialis dissolved in a solvent and coated on a substrate. As the coatingmethod, a coating method such as casting wherein the solution is simplydropped, spin coating, dip coating, blade coating, wire bar coating orspray coating, a printing method such as ink jet printing, screenprinting, offset printing or relief printing, a soft lithography methodsuch as a microcontact printing method, or a method having a pluralityof such methods combined, may be employed. Further, as a techniquesimilar to the coating, a Langmuir•Blodgett method wherein amonomolecular film formed on a water surface is transferred to andlaminated on a substrate, or a method of interposing liquid crystal ormolten liquid between a pair of substrates or introducing it between thesubstrates by a capillary phenomenon, may, for example, be mentioned.

[0178] It is advantageous to use the solution process in that an organicelectronic device having a large area can readily be prepared by arelatively inexpensive installation.

[0179] A device may also be prepared by dissolving the generalizedporphyrin compound of the present invention in a solvent, followed bycoating. In such a case, the generalized porphyrin compound to befinally used in the device, may directly be coated, but it is alsopossible to have a highly soluble compound (hereinafter referred to as aprecursor) coated and finally converted to a generalized porphyrincompound by the change of its chemical structure. This is particularlyuseful to form the material hardly soluble in a solvent into a film by acoating method.

[0180] As such a precursor, one having the following bicyclo structuremay be mentioned as a preferred example.

[0181] This bicyclo structure changes into a benzene ring bydissociation of the ethylene molecule by heating.

[0182] The bicyclo structure is sterically bulky and thus is poor incrystallizability. Molecules having this structure have good solubility,and have, in many cases, such a nature that when coated from theirsolution, a low crystalline or amorphous film can readily be obtained.When it changes into a benzene ring by the heating step, it will have amolecular structure having a good planar nature, and thus it changesinto molecules having good crystallizability. Accordingly, by utilizingthe chemical change from such a precursor, it is possible to obtain afilm having a good crystallinity by coating. This heating step may alsohave another purpose such as to distill off the coating solvent.

[0183] Particularly, among generalized porphyrin compounds of thepresent invention, a compound so-called a benzoporphyrin, having abenzene ring condensed to a pyrrole ring, a thiophene ring or a furanring, can be obtained from one having a bicyclo structure as theprecursor, and as such, it is advantageous to obtain a device bycoating.

[0184] Further, by the solution process, the semiconductor layer may bemade thick by repeating the coating and drying steps as many times asrequired. In a case where a semiconductor film is formed by conversionfrom a precursor, it is possible to form a thick film by lamination byutilizing the difference in solubility between the precursor and thesemiconductor by repeating the coating and conversion to semiconductorsteps.

[0185] Further, different film forming methods such as coating and vapordeposition, may be used in combination, or different materials may belaminated by the same or different film forming methods.

[0186] In general, it is considered that by the solution process, thefilm-forming performance is not high, and it is difficult to obtain ahighly crystalline organic semiconductor film. However, according tothis method, a highly crystalline organic semiconductor film having goodproperties can be obtained by a simple solution process, such being verydesirable. The film thus formed has a high carrier mobility and hasdesirable characteristics such that the leak current is small, and theON/OFF ratio is high. This method is an excellent method which isapplicable not only to the organic semiconductor material of the presentinvention, but widely to organic semiconductor materials in general.

[0187] (7) Post Treatment of the Semiconductor Layer

[0188] The organic semiconductor layer thus prepared may be subjected topost treatment to further improve the characteristics. For example, byheat treatment, it is possible to relax a strain in the film formedduring the film formation, whereby it is possible to improve theproperties or stability. Further, by exposing it to an oxidizing orreducing gas or liquid, such as oxygen or hydrogen, the property changeby oxidation or reduction may be induced. This may be utilized, forexample, for the purpose of increasing or decreasing the carrier densityin the film.

[0189] (8) Doping Treatment

[0190] Further, by adding a trace amount of an element, an atomic group,a molecule or a polymer by doping, it is possible to have the propertieschanged to be desirable. For example, oxygen, hydrogen, an acid such ashydrochloric acid, sulfuric acid or sulfonic acid, a Lewis acid such asPF₆, AsF₅ or FeCl₃, a halogen atom such as iodine, or a metal atom suchas sodium or potassium, may, for example, be doped. This can beaccomplished by contacting the semiconductor layer with such a gas, bydipping it in a solution, or by subjecting it to electrochemical dopingtreatment. Such doping may be carried out not only after forming thefilm but also by an addition during the preparation of the material, orin the production process from a solution, by an addition to thesolution or by an addition to the stage of a precursor film. Further, itis also possible to carry out doping by co-vapor depositing the materialto be added during the vapor deposition, by mixing the dopant to theatmosphere during the film formation, or by accelerating ions in vacuumto impinge them to the film.

[0191] The effects of such doping may, for example, be a change in theelectroconductivity due to an increase or decrease of the carrierdensity, a change in the polarity of the carrier (p-type, n-type), achange in the Fermi level, etc., and they are commonly used insemiconductor devices. Doping treatment can be likewise utilized for theorganic electronic device of the present invention.

[0192] (9) Protective Layer

[0193] In the organic electronic device of the present invention,between the respective layers or on the outer surface of the device,another layer may be provided as the case requires. For example, aprotective layer may be formed on the semiconductor layer directly orvia another layer, whereby the influence of the external atmosphere canbe minimized. Further, there is another merit that the electricalcharacteristics of the device can be stabilized. As the material for theprotective layer, the one described above may be employed.

[0194] To form the protective layer, known various methods may beemployed. However, in a case where the protective layer is made of aresin, a method of coating a resin solution, followed by drying to forma resin film, or a method of coating or vapor depositing a resinmonomer, followed by polymerization, may, for example, be employed. Itis also possible to carry out crosslinking treatment after the filmformation. In a case where the protective layer is made of an inorganicsubstance, a forming method by a vacuum process such as a sputteringmethod or a vapor deposition method, or a forming method by a solutionprocess represented by a sol gel method, may, for example, be employed.

[0195] Now, the present invention will be described in further detailwith reference to Examples. However, it should be understood that thepresent invention is by no means restricted to such specific Examples.

PREPRATION EXAMPLE 1

[0196] A bicyclo compound (1) was prepared by the following synthesisroute.

[0197] 53.5 ml of thiophenol and 51.25 g of potassium hydroxide wasdissolved in 600 ml of ethanol. To this solution, 19.4 ml ofcis-1,2-dichloroethylene was slowly dropwise added. Then, the mixturewas stirred at room temperature for 30 minutes and further heated andstirred at a temperature of from 80 to 90° C. for 23 hours. The solventwas concentrated under reduced pressure, and water was added thereto,followed by extraction with chloroform. The organic layer was washedwith water and a saturated sodium chloride aqueous solution, dried overanhydrous sodium sulfate and concentrated under reduced pressure toobtain cis-1,2-phenylthioethylene.

[0198] This cis-1,2-phenylthioethylene and 750 mg of diphenyl diselenidewere dissolved in 100 ml of methylene chloride. This solution was cooledin an ice bath, and 175 ml of a 30% hydrogen peroxide aqueous solutionwas slowly added thereto. The mixture was vigorously stirred at roomtemperature overnight, whereupon precipitated crystals were collected byfiltration, dissolved in chloroform, then washed with water, a saturatedsodium carbonate aqueous solution and a saturated sodium chlorideaqueous solution, then dried over anhydrous sodium sulfate andconcentrated under reduced pressure. Further, this product was dissolvedin 500 ml of chloroform, and while cooling the solution in an ice bath,84 g of m-chloroperbenzoate was slowly added, and the mixture wasstirred at room temperature overnight. Precipitated solid was subjectedto filtration by cerite, and the organic layer was washed with water, asaturated sodium carbonate aqueous solution and a saturated sodiumchloride solution, dried over anhydrous sodium sulfate and thenconcentrated under reduced pressure. This solid was rinsed by ethylether to obtain 67.06 g of cis-1,2-diphenylsulfonylethylene (yield:87%). Colorless crystal, mp: 100 to 101° C.

[0199] This cis-isomer and a catalytic amount of iodine were dissolvedin methylene chloride, followed by irradiation with sunlight, whereuponprecipitated solid was collected by filtration to obtaintrans-1,2-diphenylsulfonylethylene. Colorless crystals, mp: 219.5° C.

[0200] 29.33 g of trans-1,2-diphenylsulfonylethylene was dissolved in200 ml of toluene, and then, 11.4 ml of 1,3-cyclohexadiene was added,followed by dry distillation for 21 hours and then by recrystallizationto obtain 35.66 g (yield: 96.5%) of5,6-diphenylsulfonyl-bicyclo-[2,2,2]oct-2-ene.

[0201] 7.76 g of this compound was put into a reactor, and afterflushing with nitrogen, 50 ml of anhydrous tetrahydrofuran (THF) wasadded and dissolved. 2.43 ml of ethyl cyanoacetate was added thereto,and the reaction solution was cooled in an ice bath, and 50 ml of a 1Msolution of t-BuOK/THF was slowly dropwise added thereto. Thereafter,the reaction solution was returned to room temperature and stirredovernight. The reaction solution was quenched with 1N hydrochloric acidand extracted with chloroform, followed by washing with water and asaturated sodium chloride aqueous solution. Then, the organic layer wasdried over anhydrous sodium sulfate, concentrated under reduced pressureand purified by silica gel chromatography to obtain 3.49 g (yield:80.4%) of ethyl 4,7-dihydro-4,7-ethano-2H-isoindole-1-carboxylate.Colorless crystals, mp: 129-130° C.

[0202] 0.109 g of the obtained crystals were dissolved in 15 ml of THF,and 0.144 g of LiAlH₄ was dropwise added thereto at 0° C. with stirring,followed by stirring at 0° C. for 2 hours. The reaction solution wasinjected into 25 ml of water and extracted three times with 50 ml ofchloroform. The extracted solutions were put together, and 0.010 g ofp-toluenesulfonic acid was added thereto, followed by stirring at roomtemperature for 12 hours. Then, 0.150 g of p-chloranil was addedthereto, followed by stirring at room temperature for 12 hours. Then,the reaction solution was injected to water. The organic layer wasseparated and washed five times with 250 ml of an aqueous sodiumhydrogencarbonate solution, once with 250 ml of water and 100 ml of asaturated sodium chloride aqueous solution, followed by drying overmagnesium sulfate. The solvent was distilled off, and the residue waspurified by column chromatography (chloroform, alumina) to obtain 0.094g of the desired porphyrin compound (1) containing the bicyclostructure.

[0203] The main peak of m/Z=622 (M⁻) was observed by a negative ion modeof the MALDI-TOF mass spectrum.

[0204] The results (DTA-TG) of the thermal analysis of this compound areshown in FIG. 4.

[0205] Within a temperature range of from 146° C. to 198° C., a decreasein weight and heat generation are observed. This weight reduction (about18%) corresponds to detachment of four ethylene molecules from thebicyclo compound to the change into tetrabenzoporphyrin.

[0206] A chloroform solution of the porphyrin compound (1) was droppedon a gold-vapor deposited film, and the solvent was dried to form afilm. The IR spectrum of the film is shown in FIG. 5. This film washeated at 210° C. for 2 minutes, and the IR spectrum of the film isshown in FIG. 6. A change of the IR spectrum reflecting the change inthe molecular structure due to the detachment of the ethylene molecules,was observed, whereby it is evident that by the heating of the film,tetrabenzoporphyrin was formed.

[0207] The bicyclo compound (1) was heated at 210° C. for 10 minutes,and the mass spectrum thereof was measured by a negative ion mode in thesame manner as for the bicyclo compound, by the MALDI-TOF method,whereby the molecular ion peak of tetrabenzoporphyrin of m/z=510 (M⁻)was observed, whereby the change into tetrabenzoporphyrin by heating wasconfirmed. Further, the IR spectrum of this heated one, substantiallyagreed to the IR spectrum after heating, as measured on the abovesubstrate, whereby it was confirmed that one formed by the heating wastetrabenzoporphyrin.

[0208] The chloroform solution of the bicyclo compound (1) wasspin-coated on a quartz glass substrate, and the solvent was dried toform a film. This film was heated at 210° C. for 10 minutes, and thecomparison of the ultraviolet-visible light absorption spectra of thefilms before and after the heating, is shown in FIG. 7. In this Fig. thechange from the bicyclo compound to the tetrabenzoporphyrin (690 nm) isobserved as an increase in the intensity and a shift to a longwavelength side, of the Q band in the absorption spectrum of theporphyrin.

PREPARATION EXAMPLE 2

[0209] 0.02 g of the bicyclo compound (1) of Preparation Example 1 and0.1 g of zinc acetate dihydrate were put in a solvent mixture comprising30 ml of chloroform and 3 ml of methanol, followed by stirring at roomtemperature for 3 hours. The reaction solution was washed twice with 100ml of water and once with 40 ml of a saturated sodium chloride aqueoussolution. The organic phase was dried over sodium sulfate. The solventwas distilled off, and the obtained solid was recrystallized from asolvent mixture of chloroform and methanol to obtain 0.022 g of a zinccomplex of the bicyclo compound (1). Further, by gel permeationchromatography (Nippon Bunseki Kogyo JAIGEL-1H, 2H, chloroform), onlythe single peak was fractionated and purified.

[0210] The mass spectrum was measured, and the molecular peak wasconfirmed.

PREPRATION EXAMPLE 3

[0211] Preparation of 21,23-dithiaporphyrin 5

[0212] A dithiaporphyrin compound having the following bicyclo ringstructure was prepared by the following synthesis route.

[0213] Here, the starting material diformylthiophene was prepared by themethod reported in Tetrahedron Letters, vol. 43, 8485, (2002).

[0214] (1) Preparation of1,3-bis-(dihydroxymethyl)-4,7-dihydro-4,7-ethano-2-benzo[c]thiophene 2

[0215] Into a 50 ml flask, diformylthiophene 1 (0.437 g, 2.0 mmol) wasput and dissolved in 10 ml of dichloromethane and 10 ml of methanol. Theflask was cooled to 0° C. and then, NaBH₄ (0.277 g, 6.0 mmol) was added,followed by stirring for 30 minutes. The reaction solution was quenchedwith water. Then, the organic layer was extracted with dichloromethane.The organic layer was washed with water and a saturated sodium chlorideaqueous solution, then dried over sodium sulfate and concentrated. Theobtained oil was crystallized in a refrigerator and then purified byrecrystallization (CHCl₃/hexane) to obtain dihydroxymethylthiophene 2 asthe desired product in a yield of 78%. Appearance: colorless crystals,mp: 143 to 145° C.

[0216] (2) Preparation Thiatripyran Diethyl Ester 3

[0217] Into a 200 ml flask, dihydroxymethylthiophene 2 (0.888 g, 4.0mmol) and bicyclopyrrole ethyl ester (1.737 g, 8.0 mmol) were put, andafter flushing the interior of the flask with argon, dissolved in 60 mlof chloroform. This flask was cooled to 0° C., and 1 ml of TFA wasadded, followed by stirring for 1 hour and then by refluxing for 5hours. The reaction solution was poured into water and quenched. Then,the organic layer was extracted with chloroform. The organic layer waswashed with water, an aqueous sodium bicarbonate solution and asaturated sodium chloride aqueous solution and then dried over sodiumsulfate and concentrated. The obtained crude product was washed with asolvent mixture of ethyl ether and hexane and then purified byrecrystallization (CHCl₃/hexane) to obtain thiatripyran diethyl ester 3as the desired product in a yield of 90%. Appearance: slightly brownpowder (containing steric isomers), mp: >180° C. (decomposed).

[0218] (3) Preparation of Thiatripyran Dicarboxylic Acid 4

[0219] Into a 100 ml flask, thiatripyran diethyl ester 3 (0.620 g, 1.0mmol) was put and dissolved in 10 ml of tetrahydrofuran (THF), 8 ml ofethanol and 12 ml of water. LiOH.H₂O (0.840 g, 20 mmol) was added,followed by refluxing for 20 hours. The reaction solution was cooled toroom temperature, and a 1N HCl aqueous solution was slowly added, andthe pH of the solution was adjusted to 1. Then, the organic layer wasextracted with ethyl acetate. The organic layer was washed with waterand a saturated sodium chloride aqueous solution, then dried over sodiumsulfate and concentrated. The obtained crude product was washed with asolvent mixture of ethyl ether and hexane to obtain thiatripyrandicarboxylic acid as the desired product in a yield of 98%. This productwas used for the next reaction without purification. Appearance: slightbrown powder (containing steric isomers).

[0220] (4) Preparation of 21,23-dithiaporphyrin 5

[0221] Into a light-shielded 500 ml flask, thiatripyran dicarboxylicacid 4 (0.508 g, 0.9 mmol) was put, and after flushing the interior withargon, 2.5 ml of TFA was put at room temperature, followed by stirringfor 5 minutes. 200 ml of dry CH₂Cl₂ was added and then diformylthiophene(0.196 g, 0.9 mmol) was quickly added, followed by stirring at roomtemperature for 16 hours. Then, triethylamine was slowly added toneutralize the solution, and then DDQ (0.227 g, 1.0 mmol) was added,followed by further stirring for 2 hours. The obtained solution waswashed with water, a saturated sodium carbonate aqueous solution and asaturated sodium chloride aqueous solution, then dried over sodiumsulfate and concentrated. The obtained crude crystals were treated bycolumn chromatography and then purified by recrystallization(CH₂Cl₂/MeOH) to obtain dithiaporphyrin 5 as the desired product in ayield of 37%. Appearance: greenish brown solid (containing stericisomers), mp: >130° C. (decomposed). The elemental analysis, NMR andmeasurement of mass spectrum, were carried out to confirm the desiredproduct.

PREPARATION EXAMPLE 4

[0222] Preparation of 21-thiaporphyrin

[0223] In the same manner as in Preparation Example 3, thiatripyrandicarboxylic acid 4 was prepared. In the same manner as in PreparationExample 3 except that this thiatripyran dicarboxylic acid 4 and apyrrole derivative instead of thiophene were employed, a thiaporphyrincompound having the following bicyclo structure was prepared by thefollowing synthesis route.

[0224] Into a light-shielded 500 ml flask, thiatripyran dicarboxylicacid 4 (0.508 g, 0.9 mmol) was put, and after flushing the interior withargon, 2.5 ml of TFA was put at room temperature, followed by stirringfor 5 minutes. 200 ml of dry CH₂Cl₂ was added, and then, diformylpyrrole(0.181 g, 0.9 mmol) was quickly added, followed by stirring at roomtemperature for 16 hours. Then, triethylamine was slowly added toneutralize the solution, and then DDQ (0.227 g, 1.0 mmol) was added,followed by stirring for further 2 hours. The obtained solution waswashed with water, a saturated sodium carbonate aqueous solution and asaturated sodium chloride aqueous solution, then dried over sodiumsulfate and concentrated. The crude crystals were treated by columnchromatography (alumina, 50% ethyl acetate/hexane) and then purified byrecrystallization (CH₂Cl₂/MeOH) to obtain thiaporphyrin 6 as the desiredproduct in a yield of 42%. Appearance: greenish purple solid (containingsteric isomers), mp: >130° C. (decomposed). The elemental analysis, NMRand measurement of mass spectrum, were carried out to confirm thedesired product.

EXAMPLE 1

[0225] On a N-type silicon substrate (Sb-doped, resistivity: at most0.02 Ωcm, manufactured by Sumitomo Metals Industries, Ltd.) having 300nm of an oxide film formed thereon, gold electrodes (source and drainelectrodes) having a length (L) of from 2.5 to 50 μm, a width (W) of 250μm or a gap of 1,000 μm, were formed by photolithography. Further, theoxide film at a position different from these electrodes, was etchedwith a hydrofluoric acid/ammonium fluoride solution, and to the exposedSi portion, gold was vapor-deposited to form an electrode (gateelectrode) to apply a voltage to the silicon substrate.

[0226] 2 mg of the bicyclo compound (1) obtained in Preparation Example1 was dissolved in 1 ml of chloroform, and this solution was droppedbetween the source and drain electrodes, followed by evaporation of thesolvent, and this operation was repeated a few times to obtain a goodfilm. The X-ray diffraction of this film was observed, whereby no sharppeak was observed. Further, this film was observed under a crossednicols microscope, whereby a dark image over the entire surface wasobtained, thus indicating an isotropic film. Accordingly, the obtainedfilm was found to be amorphous.

[0227] This substrate was heated at 210° C. for 10 minutes. The X-raydiffraction of the obtained film was observed, whereby a sharp peak wasobserved. Further, the film was observed under a crossed nicolsmicroscope, whereby a colored domain structure was observed.Accordingly, the obtained film was found to be crystalline. Thisindicates that the bicyclo compound changed to tetrabenzoporphyrin andbecame crystalline. Further, the obtained film had a low solubility in asolvent and was hardly soluble in an organic solvent.

[0228] The characteristics of the field effect transistor thus obtainedwere measured by means of a semiconductor parameter analyzer 4155Cmanufactured by Agilent Technologies. The results of the measurement areshown in FIG. 8.

[0229] The operation may be represented as follows, wherein Id is thecurrent flowing under a voltage Vd applied across the source and thedrain, Vg is the voltage applied to the source and the gate, Vt is thethreshold voltage, Ci is the capacitance per unit area of the insulatingfilm, L is the distance between the source electrode and the drainelectrode, W is the width, and μ is the mobility of the semiconductorlayer.

[0230] When Vd<Vg−Vt,$I_{d} = {\mu \quad {{C_{i}\left( \frac{W}{L} \right)}\left\lbrack {{\left( {V_{g} - V_{t}} \right)V_{d}} - \left( \frac{V_{d}^{2}}{2} \right)} \right\rbrack}}$

[0231] when Vd>Vg,

I _(d)=(½)μC _(i)(W/L)(V ₈ −V _(t))²

[0232] Thus, the mobility μ is an important parameter of the materialgoverning the characteristics of the device (transistor), and in orderto obtain a device having high characteristics, a material having high μis required.

[0233] Inversely, μ can be obtained from the current-voltagecharacteristics of the device. To obtain μ, the formula (1) or (2) isemployed. However, for the mobility μ, there are a few definitions, i.e.an effective mobility μeff obtained from the slope of Id-Vd at a certainVg, a field effect mobility μFE obtained from the slope of Id-Vg at acertain Vd, and a saturated mobility μsat obtained from the slope ofId^(1/2)-Vg of the saturated current portion of the formula (2). Theeffective mobility μeff, the field effect mobility μFE and the saturatedmobility μsat should have the same values in the model obtained by theabove formula, and in reality, they become the same value with respectto a semiconductor material whereby ideal FET characteristics can beobtained. However, because of the difference between the real propertiesof the semiconductor material and the model, they may sometimes takedifferent values. From FIG. 8, the respective mobilities were obtained,whereby the effective mobility μeff was 1×10³ cm²/Vs, the field effectmobility μFE was 1.6×10⁻³ cm²/Vs, and the saturated mobility μsat was0.7×10⁻³ cm²/Vs.

EXAMPLE 2

[0234] Using chlorobenzene as a solvent, a film of a bicyclo compoundwas prepared in the same manner as in Example 1 and converted tobenzoporphyrin by heating.

[0235] The characteristics of the field effect transistor thus obtainedwere measured by a semiconductor parameter analyzer 4155C, manufacturedby Agilent Technologies. The effective mobility μeff was 1.6×10⁻²cm²/Vs, and the saturated mobility μsat was 1.3×10² cm²/Vs.

EXAMPLE 3

[0236] On a slide glass having aluminum vapor-deposited thereon, asolution having oxydianiline and benzophenone tetracarboxylic anhydridedissolved in dimethylformamide in a molar ratio of 1:1, was spin-coatedand heat-treated at 250° C. to prepare a polyimide film having athickness of 500 nm. On this film, a film of a bicyclo compound wasformed in the same manner as in Example 1 and converted tobenzoporphyrin by heating.

[0237] Gold was vapor-deposited thereon through a shadow mask preparedby employing a tungsten wire having a diameter of 25 μm at the gapportion, to prepare source and drain electrodes having a gap having awidth (W) of 250 μm and a length (L) of 25 μm. The characteristics ofthe field effect transistor thus obtained, were measured by asemiconductor parameter analyzer 4155C, manufactured by AgilentTechnologies. The effective mobility μeff was 3.7×10⁻² cm²/Vs, and thesaturated mobility μsat was 1.4×10⁻² cm²/Vs.

EXAMPLE 4

[0238] Using a zinc complex prepared in Preparation Example 4, FET wasprepared in the same manner as in Example 1. The characteristics of thisFET were measured, whereby the effective mobility μeff was 1.9×10⁻⁴cm²/Vs, and the saturated mobility μsat was 1.3×10⁻⁴ cm²/Vs.

EXAMPLE 5

[0239] The bicyclo compound (1) obtained in Preparation Example 1 washeated at 210° C. for 30 minutes and converted to tetrabenzoporphyrin.This product was vacuum vapor-deposited on the same electrode substrateas in Example 1 under a vacuum degree of 2×10⁻⁶ Torr (2.6×10⁻³ Pa) toprepare a field effect transistor. The relation between the substratetemperature during vacuum deposition and the mobility (the saturatedmobility) of transistor is shown in Table 1. From this relation, it isevident that the mobility differs depending upon the substratetemperature. TABLE 1 Substrate temperature Saturated mobility μsat Roomtemperature 2.9 × 10⁻⁴cm²/Vs  80° C. 2.3 × 10⁻⁶cm²/Vs 150° C. 5.6 ×10⁻⁷cm²/Vs 200° C. 2.8 × 10⁻⁸cm²/Vs

[0240] Further, in FIG. 9, with respect to ones vapor-deposited at atemperatures of 80° C. to 200° C., the X-ray diffraction patterns areshown. From the comparison of these, it is considered that crystal formsare different as between at least 150° C. and at most 80° C., and ineither case, the peak is little, and it is thus considered that the filmis strongly aligned to the substrate. Accordingly, it is considered thatthere was a substantial difference in the observed mobility.

EXAMPLE 6

[0241] The benzoporphyrin of Preparation Example 1 was subjected tochloroform/silica gel column chromatography and chloroform/methanolrecrystallization repeatedly to obtain a highly purified product. InPreparation Example 1, the purity at an absorbance at 254 nm by liquidchromatography was 99.0%, whereas with this highly purified product, itwas 99.7%.

[0242] A field effect transistor was prepared in the same manner as inExample 1 except that using this highly purified product, a precursorfilm was prepared by spin coating in a dry nitrogen and heated at 210°C. for 5 minutes in nitrogen on a hot plate.

[0243] For evaluation, a saturated mobility μsat to be calculated fromthe plotted inclination of the gate voltage and the square route of thedrain current Id, was obtained based on the relation between the gatevoltage and the current in the saturated region, whereby the saturatedmobility μsat was found to be at least 0.016 cm²/Vs. Further, the ON/OFFratio was obtained from the ratio of the drain current between in thecase of a gate voltage of 0 V and in the case of a gate voltage of −30V, at a drain voltage of −30 V, whereby the ON/OFF ratio was found to beat least 10³, and 10⁵ at best.

[0244]FIG. 10 shows the X-ray diffraction patterns of a semiconductorlayer obtained in Example 6 and a semiconductor layer prepared by vapordeposition at a substrate temperature of 150° C. in Example 5. The peaksat low angles agree to each other, whereby both appear to be similarcrystals, but the diffraction patterns are substantially different.Therefore, the states of the films such as the alignment, crystallinity,etc. are considered to be different. Accordingly, it is considered thatthe semiconductor layer obtained by coating and heating exhibitsexcellent characteristics.

EXAMPLE 7

[0245] On the device prepared in Example 6, a toluene solution ofpolymethyl methacrylate (PMMA) was spin-coated, followed by drying at120° C. to form a film of 2 μm.

[0246] To this device, and to the device prepared in Example 6, whilefixing the drain voltage at −30 V, the gate voltage was changed from 50V→−50 V→50 V, and the drain current was measured. The results are shownin FIG. 11. It is evident that even in the absence of the PMMA film, theON/OFF ratio is at least 10³ and thus shows good characteristics, but ifthe PMMA film is provided, the hysteresis of the drain current byscanning of the gate voltage is small, and also the ON/OFF ratio isimproved.

EXAMPLE 8

[0247] A FET was prepared in the same manner as in Example 1 byemploying the dithiaporphyrin prepared in Preparation Example 3. Namely,on a substrate having electrodes formed in the same manner as in Example1, a precursor having the following bicyclo structure was coated andthen heat-treated to prepare a film of tetrabenzodithiaporphyrin. Theelectrical characteristics of the FET device thus obtained weremeasured, whereby the FET characteristics were observed, and thesaturated mobility was 1.1×10⁻⁴ cm²/Vs, and the ON/OFF ratio was 1,000.

EXAMPLE 9

[0248] A FET was prepared in the same manner as in Example 1 byemploying the thiaporphyrin prepared in Preparation Example 4. Namely,on a substrate having electrodes formed in the same manner as in Example1, the precursor having the following bicyclo structure was coated andthen heat-treated to prepare a film of tetrabenzothiaporphyrin. Theelectrical characteristics of the FET device thus obtained weremeasured, whereby the FET characteristics were observed, and thesaturated mobility was 2.5×10⁻⁵ cm²/Vs, and the ON/OFF ratio was 380.

EXAMPLE 10

[0249] A FET was prepared in the same manner as in Example 1 byemploying the following zinc complex. Namely, on a substrate havingelectrodes formed in the same manner as in Example 1, a precursor havingthe following bicyclo structure was coated and then heat-treated toprepare a semiconductor film, whereby a field effect transistor wasobtained. The electrical characteristics of the FET device thus obtainedwere measured, whereby the saturated mobility μsat was 0.7×10⁻⁴ cm²/Vs,and the effective mobility μeff was 1×10⁻⁴ cm²/Vs.

COMPARATIVE EXAMPLE 1

[0250] Fields effect transistors were prepared by employing thegeneralized porphyrin compounds represented by the following respectiveformulas, and their electrical characteristics were evaluated, but ineach case, no FET characteristics were observed.

[0251] The molecular structures of these generalized porphyrin compoundswere obtained by e.g. the molecular orbital method (such as MOPAC) andthe molecular dynamics method (MM2), whereby it was confirmed that atomsconstituting the porphyrin skeleton are present at positions apart atleast 1 Å from the generalized porphyrin ring plane.

[0252] According to the present invention, an organic semiconductormaterial is used for an organic electronic device, whereby it can beproduced by a relatively low temperature process, whereby a plastic filmcan be used as the substrate, and it is possible to prepare a devicewhich is light in weight, excellent in flexibility and scarcelybreakable. Accordingly, a field effect transistor with a thin filmhaving flexibility, can be prepared, and this can be utilized for aswitching element for each cell, whereby a flexible active matrix liquidcrystal display can be prepared, and thus it is widely applicable.

[0253] Further, an organic semiconductor material and an organicelectronic device containing the generalized porphyrin compound of thepresent invention, has a high carrier mobility and stability, andfurther can be prepared by a simple production process. Further, thefield effect transistor of the present invention has a little leakcurrent and a large ON/OFF ratio and thus has a merit such that thestability of the film and characteristics is high and the useful life islong. Further, the useful temperature range is wide, the film formingproperty is good, it is applicable to a large area, and it can beprepared at low cost.

What is claimed is:
 1. An organic semiconductor material comprising acompound which has a generalized porphyrin skeleton and which has amolecular structure such that the distance from the generalizedporphyrin ring plane to the center of each atom forming the generalizedporphyrin skeleton, is not more than 1 Å.
 2. The organic semiconductormaterial according to claim 1, wherein said compound is a compound whichhas a porphyrin skeleton and which has a molecular structure such thatthe distance from the porphyrin ring plane to the center of each atomforming the porphyrin skeleton, is not more than 1 Å.
 3. The organicsemiconductor material according to claim 1, wherein the compound havinga generalized porphyrin skeleton, has a mobility of at least 1×10⁻⁵cm²/Vs.
 4. The organic semiconductor material according to claim 1,wherein the compound having a generalized porphyrin skeleton, has amolecular weight of at most 2,000.
 5. The organic semiconductor materialaccording to claim 1, wherein the compound having a generalizedporphyrin skeleton, is a benzoporphyrin.
 6. The organic semiconductormaterial according to claim 1, wherein the compound having a generalizedporphyrin skeleton, is one obtained by conversion from a precursor. 7.The organic semiconductor material according to claim 1, wherein thecompound having a generalized porphyrin skeleton, is a compoundcontaining no metal.
 8. An organic electronic device comprising asemiconductor layer and at least two electrodes, wherein thesemiconductor layer contains the organic semiconductor material asdefined in claim
 1. 9. The organic electronic device according to claim8, wherein a protective layer is formed, directly or via another layer,on the semiconductor layer.
 10. The organic electronic device accordingto claim 8, wherein the organic electronic device is a switching device.11. The organic electronic device according to claim 8, wherein theorganic electronic device is a field effect transistor.
 12. An organicsemiconductor material comprising a compound which has a generalizedporphyrin skeleton and which has a mobility of at least 1×10⁻⁵ cm²/Vs.13. The organic semiconductor material according to claim 12, whereinthe compound having a generalized porphyrin skeleton, has a molecularweight of at most 2,000.
 14. The organic semiconductor materialaccording to claim 12, wherein the compound having a generalizedporphyrin skeleton, is a benzoporphyrin.
 15. The organic semiconductormaterial according to claim 12, wherein the compound having ageneralized porphyrin skeleton, is one obtained by conversion from aprecursor.
 16. The organic semiconductor material according to claim 12,wherein the compound having a generalized porphyrin skeleton, is acompound containing no metal.
 17. An organic electronic devicecomprising a semiconductor layer and at least two electrodes, whereinthe semiconductor layer contains the organic semiconductor material asdefined in claim
 12. 18. The organic electronic device according toclaim 17, wherein a protective layer is formed, directly or via anotherlayer, on the semiconductor layer.
 19. The organic electronic deviceaccording to claim 17, wherein the organic electronic device is aswitching device.
 20. The organic electronic device according to claim17, wherein the organic electronic device is a field effect transistor.21. An organic semiconductor material comprising a compound whichcontains a structure represented by the following formula (A):

wherein n is an integer of from 4 to 20, each of X¹ to X^(n) which areindependent of one another, is a direct bond or a connecting groupconsisting of a C₁₋₃ linear unsaturated hydrocarbon group, and each ofX¹ to X^(n) which are independent of one another, may be substituted bya substituent selected from a linear alkyl group, a linear alkoxy group,a linear alkylthio group, an ester of a carboxyl group with a C₁₋₁₀linear alcohol, and a halogen atom, and an alkyl moiety of such asubstituent may further be substituted by a halogen atom, each of Y¹ toY^(n) which are independent of one another, is a π-conjugated singlering of hydrocarbon ring or heterocyclic ring, and each of Y¹ to Y^(n)which are independent of one another, may be condensed with anotherhydrocarbon ring or heterocyclic ring to form a condensed ring(hereinafter, the single rings of Y¹ to Y^(n), and the condensed ringsmade of Y¹ to Y^(n) and another ring, will be generally referred to asrings containing Y¹ to Y^(n)), each of the rings containing Y¹ to Y^(n)is an aromatic ring, which may be substituted by a substituent selectedfrom a hydroxyl group, a C₁₋₁₀ alkyl group, an alkoxy group, a mercaptogroup, an acyl group, an ester of a carboxyl group with a C₁₋₁₀ alcohol,a formyl group, a carbamoyl group, a halogen atom, an amino group whichmay be substituted by a C₁₋₁₀ alkyl group, and a nitro group, and analkyl moiety of such a substituent may further be substituted by ahalogen atom.
 22. The organic semiconductor material according to claim21, wherein in the formula (A), each of X¹ to X^(n)which are independentof one another, is unsubstituted or has a substituent composed of asingle atom such as a halogen atom.
 23. The organic semiconductormaterial according to claim 21, wherein in the formula (A), each of therings containing Y¹ to Y^(n), which are independent of one another, isunsubstituted or has a substituent composed of a single atom such as ahalogen atom.
 24. The organic semiconductor material according to claim21, wherein the molecular weight of the compound is at most 2,000. 25.The organic semiconductor material according to claim 21, wherein thecompound is one obtained by conversion from its precursor.
 26. Theorganic semiconductor material according to claim 21, wherein thecompound is a compound containing no metal.
 27. An organic electronicdevice comprising a semiconductor layer and at least two electrodes,wherein the semiconductor layer contains the organic semiconductormaterial as defined in claim
 21. 28. The organic electronic deviceaccording to claim 27, wherein a protective layer is formed, directly orvia another layer, on the semiconductor layer.
 29. The organicelectronic device according to claim 27, wherein the organic electronicdevice is a switching device.
 30. The organic electronic deviceaccording to claim 27, wherein the organic electronic device is a fieldeffect transistor.